The long-term goals of this research plan are to decipher the interacting programs of gene expression that occur in the spore-forming bacterium Bacillus subtilis. We will address a new question that has arisen in differentiating organisms, that is, how can development be used to drive and control differential gene expression? Two critical control points, called checkpoints, that coordinate gene expression during sporulation will be examined. In both mechanisms compartment-specific activation of a sigma factor is coupled to a morphological event and we plan to decipher and clarify the mechanisms for each of these. In the first developmental checkpoint involving the mother cell-specific sigma factor, sigma- K, activation is brought about by proteolytic conversion from an inactive pro-protein, pro-sigma- K, to a mature form. We plan to: 1. Identify and characterize the gene products (SpoIVFA and SpoIVFB) involved in processing of pro-sigma- K to its active form. 2. Investigate the forespore signal that activates conversion of pro-sigma K to its mature form. In the second example of a checkpoint, involving the forespore-specific sigma factor, sigma-G, the mechanism for activating the sigma factor is not, as yet, known. As a first step to elucidating the mechanism we will characterize the genes controlling this checkpoint.